Fair Value Measurements - Information about Valuation Inputs for Variable Interest Entity Assets and Liabilities Classified as Level 3 (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Estimated Future Premium Payments Weighted Average Discounted Rate	2.40%	2.70%
Asset-backed Securities [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Inputs Coupon Rate	5.97%	5.97%
Fair Value Inputs Maturity	15 years 6 months 29 days	16 years 3 months 14 days
Fair Value Inputs Yield	11.75%	12.00%
Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	$ 627		$ 3,709
Fair Value, Inputs, Level 3 [Member] | Investments [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	0		0
Fair Value, Inputs, Level 3 [Member] | European ABS Transactions [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Of Consolidated Variable Interest Entity Debt Obligations Valued Using Unobservable Inputs By Asset Class	0	$ 217
Fair Value, Inputs, Level 3 [Member] | Other Assets [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	0		0
Fair Value, Inputs, Level 3 [Member] | Derivative Financial Instruments, Liabilities [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	0		0
Loan Origination Commitments [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	851		5,946
Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	(223)		(2,237)
Investment Contracts [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Or Liability Deconsolidation Of Vies	$ 0		0
Variable Interest Entity, Primary Beneficiary [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Asset Or Liability Measured On Recurring Basis Change In Unrealized Gains Losses Still Held			$ 655
Estimated Future Premium Payments Weighted Average Discounted Rate	2.70%	3.10%
Variable Interest Entity, Primary Beneficiary [Member] | European ABS Transactions [Member]
Fair Value Inputs, Liabilities, Quantitative Information [Line Items] (Deprecated 2018-01-31)
Fair Value Inputs Coupon Rate		2.20%
Fair Value Inputs Maturity		18 years 11 months 4 days
Fair Value Inputs Yield		3.18%